Pain
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Randomized Controlled Trial
Does neonatal morphine use affect neuropsychological outcomes at 8 to 9 years of age?
Morphine is widely used to treat severe pain in neonatal intensive care unit patients. Animal studies suggest adverse long-term side effects of neonatal morphine, but a follow-up study of 5-year-old children who participated in a morphine-placebo controlled trial as newborns found no such effects on the child's general functioning. This study indicated that morphine may negatively affect response inhibition, a domain of executive functions. ⋯ After adjustment for IQ and the propensity score, executive functioning as rated by the parents remained statistically significantly better in the morphine-treated group. The influence of the additional morphine given was not of a significant influence for any of the outcome variables. Overall, the present study demonstrates that continuous morphine infusion of 10 μg/kg/h during the neonatal period does not harm general functioning and may even have a positive influence on executive functions at 8 to 9 years.
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The aim of this study was to examine whether irritable bowel syndrome (IBS) is associated with increased somatic pain sensitivity in a large population-based sample and to test whether this association was independent of sex, age, comorbid chronic pain, and psychological distress. Pain sensitivity tests included assessment of heat-pain threshold (N=4054) and pressure-pain threshold (N=4689) and of cold-pressor pain intensity and tolerance (N=10,487). Cox regression and analysis of variance (ANOVA) were used to assess the relationship between IBS and pain sensitivity in stepwise multivariate models. ⋯ Results for pressure-pain threshold were not significant. Heat- and cold-pressor pain sensitivity was greatest for the IBS reporting severe chronic abdominal pain, indicating that hyperalgesia in IBS is related to degree of clinical pain rather than to the diagnosis per se. Because all pain tests were all carried out on the upper extremities, our findings indicate the presence of widespread hyperalgesia in IBS, which may be a contributing factor to the high rate of comorbid pain seen in this patient group.
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Randomized Controlled Trial Comparative Study
Is the pain-reducing effect of opioid medication reliable? A psychophysical study of morphine and pentazocine analgesia.
A number of laboratory studies have confirmed the efficacy of opioid medication in reducing pain generated by a number of psychophysical modalities. However, one implicit assumption of clinical and experimental pain testing of analgesics is that the analgesic response is stable and will be comparable across repeated administrations. In the current study, the repeatability of opioid analgesia was assessed in a randomized, double-blinded study using 3 psychophysical pain modalities (e.g., thermal, pressure, and ischemic) over 4 medication sessions (2 with active drug, 2 with placebo). ⋯ Finally, within stimulus modalities, analgesic index scores were highly correlated with each other, suggesting that the different methods for computing analgesic responses provided comparable results. These results suggest that analgesic measures are able to distinguish between active drugs. In addition, analgesic responses to morphine and pentazocine demonstrate at least moderate reliability.
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The sexes differ with respect to perception of experimental pain. Anxiety influences pain perception more in men than in women; however, there lacks research exploring which anxiety constructs influence pain perception differentially between men and women. Furthermore, research examining whether depression is associated with pain perception differently between the sexes remains scant. ⋯ Depression was not systematically associated with pain perception in either sex. Systematic relationships were not identified that allow conclusions regarding how fear of pain, pain-related anxiety, and anxiety sensitivity may contribute to pain perception differentially in men and women; however, anxiety sensitivity was associated with increased pain tolerance, a novel finding needing further examination. The results provide directions for future research and clinical endeavors and support that fear and anxiety are important features associated with hyperalgesia in both men and women.
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Context can influence the experience of any event. For instance, the thought that "it could be worse" can improve feelings towards a present misfortune. In this study we measured hedonic feelings, skin conductance, and brain activation patterns in 16 healthy volunteers who experienced moderate pain in two different contexts. ⋯ Furthermore, the change in outcome hedonics correlated with activity in the periacqueductal grey (PAG) of the descending pain modulatory system (DPMS). The context manipulation also significantly increased functional connectivity between reward circuitry and the PAG, consistent with a functional change of the DPMS due to the altered motivational state. The findings of this study point to a role for brainstem and reward circuitry in a context-induced "hedonic flip" of pain.